Priming mixtures



Patented Mar. 31, 1936 UNITED STATES PRIMING MIXTURES Joseph Doerfer and Jacob Doerfcr, Littleton, 0010.; Jake Doerfer, also known as Jacob C. Doerfer, executor of said Joseph Doerfer, de-

ceased;

George Malcolm administrator of Jacob C. Doerfer, deceased No Drawing. Application March 22, 1933, Serial No. 662,086

3 Claims.

This invention relates to priming mixtures for ammunition, and contemplates mixtures using certain well-known oxidizers in such a way and. with such other ingredients as to substantially eliminate various disadvantages hitherto considered inherent in said oxidizers.

It is well known that for a great many years potassium chlorate was thestandard oxidizing ingredient of the priming mixture industry. Investigation into the corrosion of gun barrels, particularly the phenomenon commonly called after-corrosion, apparently established that potassium chlorate as used in priming mixtures was the agent solely responsible therefor, and the development of non-corrosive mixtures has been thought to necessarily involve the complete elimination of potassium chlorate.

The experimentation leading to the present invention has shown that potassium chlorate and its combustion residues are not in themselves necessarily harmful or rust-producing, and that the corrosion hitherto attributed to potassium chlorate is probably not due to this substance alone, but to the residues produced when certain other materials are present. The present invention therefore contemplates potassium chlorate mixtures of such a nature that little if any rusting of the bores of gun barrels is caused by their use.

The chlorate mixtures of the past have usually included a sulphide or other sulphur-containing compound. Such compounds have been largely used as priming mixture fuels, the notable examples being antimony sulphide and lead sulphocyanate, both of which have had a very extensive use for this purpose. It has now been discovered that the residues of mixtures containing both potassium clfiorate and a sulphur compound are highly corrosive, while the residues of mixtures which do not contain any sulphur compound show much less corrosion. In many instances, corrosion appears to be substantially, if not entirely, eliminated. No satisfactory theoretical explanation of this fact can at this time be offered. It is known, however, that the products of the combustion of potassium chlorate and such a fuel as antimony sulphide give an acid reaction, probably due to the presence of certain inconstant acidic salts, not fully identified. An acidic condition upon a metal surface, such as the surface of a gun bore, is known to be favorable to the formation of rust, and accordingly all mixtures containing potassium chlorate with such sulphur compounds as antimony sulphide have been found to be highly corrosive. Another possible explanation of the rust inhibiting properties of the mixtures of the present invention-is that certain protective compounds are formed which actually coat the bore surface and minimize or prevent the close contact therewith of rust accelerating residues.

One example of a non-sulphurous fuel which has been very successfully used with a potassium chlorate oxidizer is potassium ferrocyanide. The reaction of this substance with potassium chlorate yields potassium oxide, potassium chloride, ferric oxide, and carbon dioxide. The carbon dioxide and potassium oxide probably combine to form potassium carbonate. Potassium carbonate is strongly alkaline, and the residue of the combustion of this mixture has been found to be strongly alkaline, thus the substantially non-corrosive character of the mixture residues may be due to theiralkalinity. It is also possible that the potassium carbonate forms 'a protective coating which in a substantial measure keeps the potassium chloride from coming in contact with the surface of the gun bore.

Applicants do not restrict themselves to either theoretical explanation. The practical effect which they have observed is that when such a mixture of potassium chlorate and potassium ferrocyanide is fired against a polished steel plate no rusting occurs under normal atmospheric conditions of temperature and humidity, and the rusting, if any, under conditions of elevated temperature and excessive humidity is far less than that of chlorate mixtures which contain sulphur or sulphur compounds.

The mixture is preferably prepared for use in a moist condition, and its desirable properties are believed to be further enhanced by the use of certain non-aqueous moistening fluids, of which turpentine, preferably but not necessarily in the refined form sometimes called spirits of turpentine, is mentioned as an example. The use of water as a moistening fluid is believed to be undesirable. Under certain circumstances mixtures moistened with turpentine appear to undergo a certain reaction during mixing, and there is some reason to believe that this reaction is accelerated. by strong light, particularly direct sunlight. Such turpentine moistened mixtures require the application of considerable heat to effect the proper drying, a temperature of the order of 200 F. yielding the best results. The use of such a temperature accelerates the evaporation of the volatile constituents of the turpentine, leaving a resinous residue possessing fuel properties'and possibly also serving as a binder. At materially lower temperatures the evaporation of the turpentine is greatly retarded. The value of turpentine as a priming mixture ingredient is surprising in view of the known deadening and phlegmatizing properties of turpentine and other oils when applied to explosives generally. Its desirable properties in priming mixtures may be due to a decomposition reaction of the turpentine itself or its reaction with the other ingredients of the mixture during and/or subsequent to the drying at an elevated temperature.

Both potassium chlorate and potassium ferrocyanide being relatively soft materials, it has been found desirable, in order to secure ready ig nition by impact, to add to the mixture a quantity of glass power. Thus, a typical and illustrative formula for a successful and substantially noncorrosive priming mixture is as follows:

Percent Potassium chlorate 48 Potassium ferrocyanide 36 Glass 16 altered. A typical formula is Percent Potassium chlorate 53% Potassium ferrocyanide; 33

A small amount of a coloring matter, such as lamp black or Prussian blue, may be added, for the purpose of facilitating inspection of the thoroughness of mixing. It is believed desirable, however, to avoid the addition of any material which may contain sulphur, even in small quantities.

The present invention is believed to comprise the first discovery of the usefulness of turpentine as a priming mixture moistening agent, as well as the first discovery of the substantially noncorrosive character of mixtures containing potassium chlorate and non-sulphurous fuels; hence, the appended claims are to be broadly construed.

What is claimed is:

1. A priming mixture for ammunition consisting of potassium chlorate, potassium ferrocyanide and an abrasive, the combustion of said mixture under the conditions existing in a small arms cartridge resulting in a residue which substantially inhibits the normal corrosive action of the residues of mixtures containing potassium chlorate.

2. A priming mixture for small arms ammunition consisting of an inert abrasive, potassium chlorate as an oxidizer, and potassium ferrocyanide as a fuel, said. potassium ferrocyanide being present in a quantity suflicient to substantially retard the corrosiveaction of the reduction residues of potassium chlorate.

3. A priming mixture for small. arms ammunition consisting'of Percent Potassium chlorate 48 -5 3'} 35 Potassium ferrocyanide aising; 33% -,36 Glass 15 JOSEPH DOERFEB. JACOB P W- 

